(x-2y)(y-3x)+(x+y)(x-3y)-(y-3x)(4x-5y);
=(xy-3x²-2y²+6xy)+(x²-3xy+xy-3y²)-(4xy-5y²-12x²+15xy);
=7xy-3x²-2y²+(x²-2xy-3y²)-(19xy-5y²-12x²);
=7xy-3x²-2y²+x²-2xy-3y²-19xy+5y²+12x²;
=(-3+1+12)x²+(7-2-19)xy+(-2-3+5)y²;
=10x²-14xy;
=2x(5x-7y)
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Объяснение:
